1. Field of the Invention
The present invention relates to a rotary-motor-loaded device and control characteristic measurement method and program for measuring data which is required for computing control characteristics of a motor drive control unit which controls a rotary motor for rotating a rotation object at a predetermined revolution speed; and, particularly relates to a rotary-motor-loaded device and control characteristic measurement method and program for measuring the data required for computing the control characteristics by generating disturbance in control of a spindle motor by the device per se.
2. Description of the Related Arts
Conventionally, in a test process in the stage of manufacturing a magnetic disk device which is an example of a rotary-motor-loaded device, spot measurement and evaluation of control characteristics of a servo combo chip (SVC chip) which is a circuit chip having functions of a spindle motor driver, etc. of rotating magnetic disk media at a constant speed are performed. Methods for measuring the control characteristics of the SVC chip includes a method in which measurement is performed when the SVC chip is loaded on a board which is dedicated to evaluation and a method in which measurement is performed by use of a printed board of a device on which the SVC chip is mounted. When the measurement method using the board for evaluation is used, external data is input as signals through a signal input pin so as to generate disturbance in the revolution speed of the spindle motor. Meanwhile, in the case of the measurement method using the printed board on which the SVC chip is mounted, printed wiring is lead out from the surface of the printed board so as to input external data as signals and generate disturbance in the revolution speed of the spindle motor. In evaluation of the control characteristics in such measurement tests, in either method, the response revolution speed upon disturbance generation is measured by utilizing a measuring instrument such as an oscilloscope so as to detect measured data by plotting it, and gain characteristics and phase characteristics of the SVC chip are obtained from response data with respect to the disturbance variation, thereby evaluating them.
However, in such conventional measurement methods of the control characteristics of the SVC chip, it has become extremely difficult to measure and evaluate control characteristics of the SVC chip by use of dedicated evaluation boards and printed boards of devices since everything about a disk rotation control system according to a spindle motor is incorporated in a chip in recent SVC chips, and as package structures of SVC chips, leadless ball grid arrays (Ball Grid Array), QFN packages (Quad Flat Non-Leaded Package), etc. which do not have lead pins and are suitable for high-density packaging are used.